The present invention relates generally to a reciprocating internal combustion engine with a variable compression ratio mechanism including a multiple-link type piston crank mechanism, and more particularly to an improvement in a lubrication system of the engine.
Recent years, there have been disclosed various variable compression ratio mechanisms of a reciprocating internal combustion engine with a multiple-link type piston crank mechanism which are capable of varying the top dead center (TDC) position and/or the bottom dead center (BDC) of a piston and the engine compression ratio by displacing a part of elements of the linkage. One such mechanism is disclosed in Japanese Patent Provisional Publication No. 2002-21592 published Jan. 23, 2002 (corresponding to U.S. Pat. No. 6,505,582 assigned to the assignee of the present invention Jan. 14, 2003). This variable compression ratio mechanism includes an upper link connected at one end to a piston with a piston pin, a lower link oscillatably or rockably pin-connected to the other end of the upper link with an upper pin and rotatably attached to a crankpin of a crankshaft, a control link oscillatably pin-connected at one end to the lower link with a control pin, a control shaft rotatably mounted onto a cylinder block and having an eccentric cam oscillatably supporting the other end of the control link, for varying the engine compression ratio by regulating the position of the eccentric cam of the control shaft according to an engine operating condition.